Wakanomori took me to Holyoke's secret stream, which runs beneath Interstate 91. There's a park there, but these boys preferred the actual stream (so did a chipmunk and an oriole I saw).

At one end of the present-day park is a closed roadway that leads up into an overgrown, abandoned park. If you climb up and up, you reach this tower that looks like it took its design cues from rude graffiti:

You can climb up a literally falling-apart concrete spiral staircase on the inside of the, uh, shaft, and up top there is a glorious view of the surrounding countryside. Which I didn't take a picture of! I was too busy recovering from the hair-raising ascent. Fortunately, Wakanomori took a picture. He also obliged me by taking pictures of the words of wisdom inscribed there, and of some of the community-created artwork at the base of the tower.